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Soil priming is a microbial-driven process, which determines key soil–climate feedbacks in response to fresh carbon inputs. Despite its importance, the microbial traits behind this process are largely undetermined. Knowledge of the role of these traits is integral to advance our understanding of how soil microbes regulate carbon (C) emissions in forests, which support the largest soil carbon stocks globally. Using metagenomic sequencing and C-glucose, we provide unprecedented evidence that microbial traits explain a unique portion of the variation in soil priming across forest biomes from tropical to cold temperature regions. We show that microbial functional profiles associated with the degradation of labile C, especially rapid simple sugar metabolism, drive soil priming in different forests. Genes involved in the degradation of lignin and aromatic compounds were negatively associated with priming effects in temperate forests, whereas the highest level of soil priming was associated with β-glucosidase genes in tropical/subtropical forests. Moreover, we reconstructed, for the first time, 42 whole bacterial genomes associated with the soil priming effect and found that these organisms support important gene machinery involved in priming effect. Collectively, our work demonstrates the importance of microbial traits to explain soil priming across forest biomes and suggests that rapid carbon metabolism is responsible for priming effects in forests. This knowledge is important because it advances our understanding on the microbial mechanisms mediating soil–climate feedbacks at a continental scale., This work were financially supported by the National Natural Science Foundation of China (41907031), the Chinese Academy of Sciences “Light of West China” Program for Introduced Talent in the West, the National Natural Science Foundation of China (31570440, 31270484), the Key International Scientific and Technological Cooperation and Exchange Project of Shaanxi Province, China (2020KWZ-010), the 2021 First Funds for Central Government to Guide Local Science and Technology Development in Qinghai Province (2021ZY002), the i-LINK +2018 (LINKA20069) from CSIC, and a Ramón y Cajal grant from the Spanish Ministry of Science and Innovation (RYC2018-025483-I)

Soil microorganisms play an important role in the circulation of materials and nutrients between plants and soil ecosystems, but the drivers of microbial community composition and diversity remain uncertain in different vegetation restoration patterns. We studied soil physicochemical properties (i.e., soil moisture, bulk density, pH, soil nutrients, available nutrients), plant characteristics (i.e., Shannon index [HPlant] and Richness index [SPlant], litter biomass [LB], and fine root biomass [FRB]), and microbial variables (biomass, enzyme activity, diversity, and composition of bacterial and fungal communities) in different plant succession patterns (Robinia pseudoacacia [MF], Caragana korshinskii [SF], and grassland [GL]) on the Loess Plateau. The herb communities, soil microbial biomass, and enzyme activities were strongly affected by vegetation restoration, and soil bacterial and fungal communities were significantly different from each other at the sites. Correlation analysis showed that LB and FRB were significantly positively correlated with the Chao index of soil bacteria, soil microbial biomass, enzyme activities, Proteobacteria, Zygomycota, and Cercozoa, while negatively correlated with Actinobacteria and Basidiomycota. In addition, soil water content (SW), pH, and nutrients have important effects on the bacterial and fungal diversities, as well as Acidobacteria, Proteobacteria, Actinobacteria, Nitrospirae, Zygomycota, and microbial biomass. Furthermore, plant characteristics and soil properties modulated the composition and diversity of soil microorganisms, respectively. Overall, the relative contribution of vegetation and soil to the diversity and composition of soil bacterial and fungal communities illustrated that plant characteristics and soil properties may synergistically modulate soil microbial communities, and the composition and diversity of soil bacterial and fungal communities mainly depend on plant biomass and soil nutrients.

Litter decomposition is the main source of soil organic carbon (SOC) pool, regarding as an important part of terrestrial ecosystem C dynamics. The turnover of SOC is mainly regulated by extracellular enzymes secreted by microorganisms. However, the response mechanism of soil C-degrading enzymes and SOC in litter decomposition remains unclear. To clarify how SOC fraction dynamics respond to C-degrading enzymes in litter decomposition, we used field experiments to collect leaf litter and SOC fractions from the underlying layer in Robinia pseudoacacia plantations on the Loess Plateau. Our results showed that soil SOC, easily oxidizable organic C, soluble organic C and microbial biomass C increased significantly during the decomposition process. Litter decomposition significantly decreased soil hydrolase activity, but slightly increased oxidase activity. Correlation analysis results showed that SOC fractions were significantly positively correlated with the litter mass, lignin, soil moisture, and oxidase activity, but significantly negatively correlated with cellulose content and soil pH. Partial least squares path models revealed that the most direct factors affecting the SOC fractions of topsoil during litter decomposition were litter lignin and cellulose degradation, soil pH, and C-degrading enzymes. Furthermore, regression analysis showed that the decrease of SOC stability in litter decomposition was closely related to the decrease of soil hydrolase: oxidase ratio. These results highlighted that litter degradation-induced changes in C-degrading enzyme activity significantly affected SOC fractions. Furthermore, the distribution of soil hydrolase and oxidase modulated the stability of SOC during litter decomposition. These findings provided a theoretical framework for a more comprehensive understanding of C turnover and stabilization mechanisms between plant and soil.

Aims Plant nutrient requirements (NRs) and acquisition strategies are critical to understand the net primary productivity and community stability in terrestrial ecosystems; however, the current knowledge on this subject is limited, especially in cases of afforestation. Methods We selected one farmland and four Robinia pseudoacacia (RP) forests (15-, 21-, 31-, and 46-years-old) to investigate the changes in plant NRs and evaluate the effectiveness of acquisition strategies (including nutrient resorption and soil nutrient formed by mineralization) after afforestation in the Loess Plateau. We analyzed the nutrients in plant organs, litter, and soil, along with the extracellular enzyme activities (EEAs), microbial biomass, and mineralization rate. In addition, the biomass of RP was determined using an allometric growth model. Results During afforestation, the nitrogen and phosphorus requirement of RP increased significantly, from 3.97 to 18.14 g·m− 2·year− 1 and 0.17 to 0.71 g·m− 2·year− 1, respectively. However, the contributions of nutrient resorption to the total NR were lower than 50% and decreased significantly with stand age. Additionally, partial correlation analysis indicated that soil EEAs were the factors directly affecting the mineralization process. PLS-PM revealed that afforestation promotes the microbial biomass by increasing soil nutrients, leading to the secretion of more extracellular enzymes, which ultimately results in an increase in the soil mineralization rate. Conclusions Our study highlights the importance of soil mineralization for plant NRs and clarify the effects of afforestation on soil mineralization processes. Our study contributes to a better understanding of plantation nutrient cycling and, thus, facilitates efficient forest management practices.

9 páginas.- 4 figuras.- 41 referencias.- Additional supporting information may be found in the online version of the article at the publisher’s website., Aim Fresh carbon (C) inputs to the soil can have important consequences for the decomposition rates of soil organic matter (priming effect), thereby impacting the delicate global C balance at the soil-atmosphere interface. Yet, the environmental factors that control soil priming effect intensity remain poorly understood at a global scale. Location Global. Time period 1980-2020. Major taxa studied Soil priming effect intensity. Methods We conducted a global dataset of CO2 effluxes in 711 pairwise soils with C-13 or C-14 simple C sources inputs and without C inputs from incubation experiments in which isotope-labelled C was used to quantify fresh C-induced rather than exudate-induced priming. Results Soil priming effect intensity is predominantly positive. Soil texture and C content were identified as the most important factors associated with priming effects, with sandy soils from tropical and mid-latitudes supporting the highest soil priming effect intensity, and soils with greater C content and fine textures from high latitudes maintaining the lowest soil priming effects. The negative association between C content and soil priming effect intensity was also indirectly driven by changing mean annual temperature, net primary productivity, and fungi : bacteria ratio. Using this information, we generated a global map of soil priming effect intensity, and found that the priming was lower at high latitudes and higher at lower latitudes. Main conclusions Global patterns of soil priming effect intensity can be predicted using environmental data, with soil texture and C content playing a predominant role in explaining in priming effects. These effects were also indirectly driven by climate, vegetation and soil microbial properties. We present the first global atlas of soil priming effect intensity and advance our knowledge on the potential mechanisms underlying soil priming effect intensity, which are integral to improving the climate change and soil C dynamics components of Earth System models., National Natural Science Foundation of China, Grant/Award Number: 41907031; China Postdoctoral Science Foundation, Grant/Award Number: 2021T140565; Natural Science Basic Research Plan in Shaanxi Province of China, Grant/Award Number: 2020JQ-272; Forest and Grass Technology Innovation Development and Research Projects from National Forestry and Grassland Administration, Grant/Award Number: 2020132111; China Postdoctoral Science Foundation, Grant/Award Number: 2019M650276; Chinese Academy of Sciences “Light of West China” Program for Introduced Talent in the West, Grant/Award Number: 31570440

Afforestation has significantly affected interactions between soil nutrients and microbial enzymes. To understand the detailed variations in extracellular enzyme activity and their link with soil nutrient availability after returning farmland (FL) to forest, soil samples were collected from FL and three afforested lands, Robinia pseudoacacia L. forest (RP), Caragana korshinskii Kom. forest (CK), and abandoned land (AL) in the Loess Hilly Region of northern China. The soil enzymes: β-glucosidase (BG), N-acetylglucosaminidase (NAG), alkaline phosphatase (AP), and leucine aminopeptidase (LAP); their stoichiometric ratios; and soil properties such as soil organic carbon, total nitrogen (TN), total phosphorus (TP), dissolved organic carbon, dissolved organic nitrogen, available phosphorus, soil moisture content (SMC), soil bulk density, and pH were measured. The BG activity showed similar trends as AP activity during afforestation, reaching the highest level in CK and showing a value 205% higher than that in FL. The NAG and LAP activities were not altered by afforestation; only the (NAG + LAP) : AP ratio decreased significantly by 44 to 60%. The BG : AP and (NAG + LAP) : AP ratios were strongly correlated with pH. Compared with other soil physicochemical properties, the soil moisture content greatly affected soil enzyme activity. The most relevant nutrients for the enzymes and stoichiometry were TN and TN : TP. Thus, our results suggest that soil enzyme activity and its stoichiometry are sensitive to changes in soil physical and chemical properties and total soil nutrients content, particularly pH, SMC, TN, and TN : TP.

Succession is one of the central themes of ecology; however, the relationship between aboveground plant communities and underground soils during secondary succession remains unclear. In this study, we investigated the composition of plant community, plant-soil C:N:P stoichiometry and their relationships during secondary succession after the abandonment of farmlands for 0, 10, 20, 30, 40 and 50 a in China, 2016. Results showed that the composition of plant communities was most diverse in the farmlands after secondary succession for 20 and 50 a. Soil organic carbon and total nitrogen contents slightly decreased after secondary succession for 30 a, but both were significantly higher than those of control farmland (31.21%–139.10% and 24.24%–121.21%, respectively). Moreover, C:N ratios of soil and microbe greatly contributed to the changes in plant community composition during secondary succession of abandoned farmlands, explaining 35.70% of the total variation. Particularly, soil C:N ratio was significantly and positively related with the Shannon-Wiener index. This study provides the evidence of synchronous evolution between plant community and soil during secondary succession and C:N ratio is an important linkage between them.

Soil Phosphorous (P) availability is a limiting factor for plant growth and regulates biological metabolism in plantation ecosystems. The effect of variations in soil microbial P cycling potential on the availability of soil P during succession in plantation ecosystems is unclear. In this study, a metagenomics approach was used to explore variations in the composition and diversity of microbial P genes along a 45-year recovery sequence of Robinia pseudoacacia on the Loess Plateau, as well soil properties were measured. Our results showed that the diversity of P cycling genes (inorganic P solubilization and organic P mineralization genes) increased significantly after afforestation, and the community composition showed clear differences. The gcd and ppx genes were dominant in inorganic P transformation, whereas phnM gene dominated the transformation of organic P. The abundance of genes involved in inorganic P solubilization and organic P mineralization was significantly positively correlated with P availability, particularly for phnM, gcd, ppx, and phnI genes, corresponding to the phyla Gemmatimonadetes, Acidobacteria, Bacteroidetes, and Planctomycetes. The critical drivers of the microbial main genes of soil P cycling were available P (AP) and total N (TN) in soil. Overall, these findings highlight afforestation-induced increases in microbial P cycling genes enhanced soil P availability. and help to better understand how microbial growth metabolism caused by vegetation restoration in ecologically fragile areas affects the soil P cycling.

Browser fingerprinting is a practical user tracking technology widely adopted by many real-world websites to potentially track users’ browsing behaviors. By collecting information such as screen resolution, user agent, and WebGL rendered data, the tracker can generate a unique identifier for users without their knowledge, leading to a severe violation of user privacy. Therefore, an effective detection and defense technology for browser fingerprinting is needed to protect user privacy. In this paper, we proposed FPFlow, a dynamic JavaScript taint analysis framework to detect and prevent browser fingerprinting. FPFlow monitors the whole process of browser fingerprinting, including collecting information, generating fingerprinting, and sending it to the remote server. We evaluated FPFlow on TRANCO top 10,000 websites. Our experiments showed that our framework could effectively detect browser fingerprints. We found 66.6% of the websites performing fingerprinting and revealed how browser fingerprinting is applied in real-world websites. We also showed that FPFlow could prevent browser fingerprinting with an acceptable overhead.

Afforestation can modify terrestrial carbon (C) pools, some of which are primarily fixed in the plant dead biomass and then incorporated into the microbial dead biomass. Soil microorganisms exert a critical role in C flow and potentially influence C balance through the degradation of plant and microbial dead biomass. Here, we compared sites along a 45-year Robinia pseudoacacia (RP) afforestation chronosequence on the Loess Plateau of China. Subsequently, the trends of microbial carbohydrate-active enzymes (CAZyme) and their responses to the decomposition of dead biomass of different origins were studied using metagenomics. The results show that soil microbial CAZyme families, which degrade the plant- and microbial-derived components, significantly increased after afforestation, with a significant peak at the 20-year site. The dominant bacterial phyla (i.e., Actinobacteria, Proteobacteria, and Acidobacteria) mineralized C sources from plant and microbial biomass components through their corresponding CAZyme families. Moreover, the increased abundance of CAZymes involved in the decomposition of plant-derived components (e.g., cellulose, hemicellulose, and lignin) contributed to the formation of C pools. In the case of microbial-derived components, the abundance of CAZymes encoding the bacterial-derived components (peptidoglycan) was larger than that encoding fungal-derived components (chitin and glucans) and was more associated with microbial metabolic activity (qCO2 and Cmic: Corg ratio), indicating a higher investment of bacterial-derived components for microbial carbon turnover following afforestation. Overall, our study compares plant- and microbial-derived biomass to illustrate the differential contributions of dead biomass to C accumulation and confirms the importance of the bacterial community and derived biomass for C turnover following afforestation.

Ecological stoichiometry is the study of mass balance of multiple chemical elements in ecosystems; it analyzes the constraints and consequences of these mass balances during ecological processes, based on universal laws of physics, chemistry, and biology. To understand the variation in stoichiometry characteristics of Robinia pseudoacacia of different planting ages, and determine the main soil factors influencing stoichiometry characteristics of R. pseudoacacia, relationships between leaf and branch stoichiometry and soil nutrient characteristics in R. pseudoacacia communities of different planting ages were analyzed in this study. Results showed that: (1) with increasing planting age, the C, N, P contents in leaves and branches, as well as the N/P ratio in leaves increased initially and then decreased, with the highest value in 40a (40 years old). The C/N and C/P ratios in leaves and in branches decreased initially and then increased with the increase of planting age. The N, P contents, and C/N and C/P ratios in leaves had nonlinear relationships with R. pseudoacacia age. The average N, P contents, and C/N, C/P ratios in leaves were affected significantly by planting age (P > 0.05). (2) With increasing planting age, soil C, N, P contents, and C/P, N/P ratios in R. pseudoacacia communities increased initially and then decreased. (3) Soil total N content was the main factor influencing C and N contents in leaves and C, N, P contents and C/P ratio in branches. The C, P contents and C/N, C/P ratios in leaves and C/N ratio in branches were influenced by the soil N/P ratio. The C content and N/P ratio in leaves were affected by the soil organic C content. In conclusion, with increasing planting age, 12 stoichiometry characteristic indices in R. pseudoacacia communities and soil increased initially and then decreased. Stoichiometry characteristic indices in R. pseudoacacia communities showed the highest value in 40a. Stoichiometry characteristic indices in R. pseudoacacia were mainly affected by soil total N content, the N/P ratio, and organic C content.

Soil samples were collected in June and October from areas with three land-use types, i.e., Robinia pseudoacacia L. (RP), Caragana korshinskii Kom. (CK), and abandoned land (AL), of which the former two were afforested areas, whereas the latter was not. These areas were converted from similar farmlands 40 years prior. Illumina sequencing of 16S rRNA gene and fungal ITS gene was used to analyze soil bacterial and fungal diversity. Additionally, plant communities, soil properties, fine root biomass, and C, N, and P levels in fine root and microbial biomass were estimated. Compared to AL, the C:N:P stoichiometry in fine root and microbial biomass in the afforested lands was synchronously changed, especially the N:P ratio. Soil microbial diversities were affected by afforestation and were more related to N:P ratio than C:P and C:N ratios. Moreover, Alpha-proteobacteria, Gamma-proteobacteria, and Bacteroidetes were significantly more abundant in afforested soils than in the AL soil, and the abundances of Actinobacteria, Chloroflexi, Cyanobacteria, and Nitrospirae ranked as AL > RP or CK. For fungal taxa, Ascomycota abundance responded positively to afforestation, whereas Basidiomycota abundance responded negatively. Changes of soil microbial taxa were significantly correlated with the N:P ratio in fine root and microbial biomass, which explained 54.1 and 55% of the total variation in bacterial and fungal taxa, respectively. Thus, our results provide evidence that compositions of soil microbial communities are linked to the N:P ratio in the plant-soil system.

Web-based cryptocurrency mining attacks, also known as cryptojacking, become increasingly popular. A large number of diverse platforms (e.g., Windows, Linux, Android, and iOS) and devices (e.g., PC, smartphones, tablets, and even critical infrastructures) are widely impacted. Although a variety of detection approaches were recently proposed, it is challenging to apply these approaches to attack prevention directly.Instead, in this paper, we present a novel generic and accurate defense solution, called “MinerGate”, against cryptojacking attacks. To achieve the goal, MinerGate is designed as an extension of network gateways or proxies to protect all devices behind it. When attacks are identified, MinerGate can enforce security rules on victim devices, such as stopping the execution of related JavaScript code and alerting victims. Compared to prior approaches, MinerGate does not require any modification of browsers or apps to collect the runtime features. Instead, MinerGate focuses on the semantics of mining payloads (usually written in WebAssembly/asm.js), and semantic-based features.In our evaluation, we first verify the correctness of MinerGate by testing MinerGate in a real environment. Then, we check MinerGate’s performance and confirm MinerGate introduces relatively low overhead. Last, we verify the accuracy of MinerGate. For this purpose, we collect the largest WebAssembly/asm.js related code with ground truth to build our experiment dataset. By comparing prior approaches and MinerGate on the dataset, we find MinerGate achieves better accuracy and coverage (i.e., 99% accuracy and 98% recall). Our dataset will be available online, which should be helpful for more solid understanding of cryptojacking attacks.

Variability in soil enzyme activity may have important implications for the knowledge of underground ecosystem functions driven by soil extracellular enzymes. To illustrate the temporal variation in soil enzyme activity after afforestation, we collected soil samples during different vegetative growth periods in three Caragana korshinskii Kom. stands of different ages (20, 30, and 40 years) and in a slope cropland in the Loess Plateau. These samples were used to analyze the catalase, sucrase, urease and alkaline phosphatase activities, the soil water content and the available soil nutrients (i.e., dissolved organic carbon, dissolved organic nitrogen, and available phosphorus). The results illustrated that the soil enzyme activities significantly increased following afforestation and varied with temporal variation. Overall, soil enzyme activities were higher in June and August, particularly, and both alkaline phosphatase and sucrase were more sensitive to temporal variation than the other two enzymes. In addition, redundancy analysis showed that soil enzyme activities were greatly correlated with soil nutrients, especially for dissolved organic carbon and dissolved organic nitrogen. Therefore, the results highlighted the importance of soil enzyme activities to soil nutrients under temporal variation following afforestation in the Loess Plateau, which may have practical significance for forest managers&rsquo, fertilization management of plantation in different seasons and different stand ages.

Plant nitrogen (N) and phosphorus (P) resorption is an important strategy to conserve N and P in the face of nutrient limitation. However, little is known about the variation of N and P resorption efficiency (NRE and PRE) and their correlation with leaves and soil C:N:P stoichiometry in black locust forests (Robinia pseudoacacia L.) of different ages. In this study, we measured C, N, and P concentrations in soil, green leaves, and senesced leaves from black locust forests of different ages (i.e, 10-, 20-, 30-, 36-, and 45-year-old), and calculated the NRE, PRE, and C:N:P stoichiometry ratios. The NRE and PRE tended to increase and then decrease with stand age, ranging from 46.8% to 57.4% and from 37.4% to 58.5%, with averages of 52.61 and 51.89, respectively. The PRE:NRE decreased with increased stand ages. The C:P and N:P of soil and green leaves increased with stand ages, indicating the increase of P limitation. In the senesced leaves, C:P and N:P were lower than in green leaves and first increased and then decreased with stand age. The PRE was significantly negatively correlated with the C:P and N:P of soil and green leaves. The NRE was significantly correlated with the C concentration of green leaves, P of the senesced leaves, and C:N. Results suggested that the NRE and PRE responded differently to soil and plant nutrients in black locust forests of different ages. In addition, the black locust plantations would alter the conservation and use strategy of nutrients in the ecosystem through a plant-mediated pathway. Future studies should elucidate the central nutrient utilization strategy of black locust in response to a nutrient-poor environment and determine how it is involved in regulating nutrient resorption.

The positive impact of straw incorporation (S1) on mitigating global warming potential due to increase soil organic carbon sequestration can be offset by the straw-induced greenhouse gas (GHG) emissions. Therefore, this study advocated an optimal straw-based system, i.e. straw incorporation plus half plastic film mulch (SP), to mitigate the straw-induced GHG emissions in northwest China. A two-year field experiment was conducted to investigate effects of no straw inputs (S0), S1 and SP on yields, GHG emissions and soil labile carbon (C) and nitrogen (N) pools, and identify the relationship between GHG emissions and soil labile C and N pools. Results showed that SP significantly enhanced maize yield by 14.5 and 7.0% in 2018 and 2019, respectively, as compared to S0, mainly due to the increased soil inorganic nitrogen (SIN) and dissolved organic nitrogen (DON) contents. In addition, SP considerably mitigated the straw-induced CO2 emission by 77.8 and 67.1% in 2018 and 2019, respectively, mainly attributed to the reduced dissolved organic carbon (DOC)/DON, microbial biomass carbon (MBC)/SIN and DOC/SIN. Moreover, SP significantly lessened the straw-induced N2O emission by 43.6 and 59.5% in 2018 and 2019, respectively, due to significant decreased DOC content during seeding to jointing, the major N2O emission period. Our results indicated that SP, as a kind of straw-based system, enhanced the sustainability of summer maize ecosystem because of mitigating the straw-induced GHG emissions and simultaneously enhancing maize yield.

The stimulated N2O emission by straw incorporation (S 1 ) is adverse to mitigating global warming potential (GWP). Thus, this study advocated an optimal straw-based system, i.e. S 1 plus biochar (SB), to mitigate the straw-induced N2O emission and further promote soil organic carbon (SOC) sequestration. Moreover, this study addressed research gap on quantification of soil quality focused on enhancing yield and alleviating GWP. Greenhouse gas emission intensity (GHGI) was used to relate yield with GWP. A field experiment was conducted to investigate the response of overall soil quality to S 1 , SB and no straw inputs (S 0 ) under two nitrogen rates (routine rate [N1] and 70% of routine rate [N 0.7 ]). To comprehensively evaluate soil quality, a wide range of soil physical, chemical, biological and ecological properties closely related to yield and GHGI were measured and integrated into a soil quality index (SQI). Although both S 1 and SB enhanced the SQI, the SB achieved the highest SQI under N 1 rate. Firstly, this is because N 1 -SB significantly mitigated the straw-induced N2O emission, associated with the declined soil inorganic nitrogen (SIN) and dissolved organic carbon (DOC) contents. Secondly, N 1 -SB greatly enhanced SOC sequestration, mainly attributed to the increased ratio of microbial biomass carbon to microbial biomass nitrogen (MBC/MBN) and decreased microbial quotient (MBC/soil organic carbon and MBN/total nitrogen), implying the lower efficiency of soil microorganisms to utilize soil organic matter. Lastly, N 1 -SB markedly increased maize yield in 2019 compared to S 0 . Overall, the highest SQI for N 1 -SB was ascribed to the higher soil quality scores in labile nitrogen/total nitrogen (LN/TN) and MBC/MBN, and lower soil quality scores in SIN and DOC.

Reforestation or natural forest regeneration is an alternative measure for controlling soil erosion in degraded land on the Chinese Loess Plateau (CLP). However, our understanding of the temporal dynamics and the spatial patterns of forest regeneration remains inadequate. Two oak forests at different development stages were investigated to determine the spatial patterns of competitions (intraspecies and interspecies) during different successional stages. The intraspecies and interspecies spatial relationships among different tree diameters at breast height were analyzed at multiple scales by Kriging interpolation method and univariate and bivariate O-ring statistics. Our analytical results indicated that self-correlation and competition intensity were relatively high between oak and pine trees in the early development stage of oak forests due to their clumped distributions of heavy seeds. Birch trees had a lower competition in comparison to oak trees although birch was the dominant species. Therefore, asymmetric competition of oak trees was most likely to have led to their edge dispersal and their success in replacing the pioneer species. Asymmetric competition means that larger individuals obtained a disproportionately large share of the resources and suppressed the growth of smaller individuals. Kriging interpolation analysis showed a tendency towards homogenization caused by interspecies competition during the succession of oak forests. Our results demonstrated that the competition was the driving factor in the spatial distribution of oak forests on the CLP.

Afforestation has been proven to have enormous potential for carbon (C) sequestration; however, the dynamics of aggregate-associated organic carbon (OC) following afforestation and their contribution to changes in bulk soil OC are not well understood in regions with serious soil erosion. Therefore, we investigated the dynamics of OC associated with aggregates along a Robinia pseudoacacia (RP) afforestation chronosequence in the Loess Plateau. Soil aggregate size distribution and OC dynamics in bulk soil were analyzed 10, 18, 28, and 42 years after RP afforestation at depths of 0-20 cm and 20-40 cm. Results showed that total macroaggregates (0.25 mm), mean weight diameter, and geometric mean diameter increased significantly with stand age, after 42 years of afforestation, increased by 433.5%, 437.2%, 302.1% in the 0-20 cm depth, respectively, while microaggregate amounts decreased by 52.9%, and the proportions of silt + clay fraction showed no obvious changes. Long-term afforestation increased OC content and stock, both in bulk soil (245.6% and 222.9% in the 0-20 cm depth, respectively) and soil aggregates. The improvement of soil structure and enrichment of OC stocks were greater at the 0-20 cm depth than the 20-40 cm depth. In addition, small macroaggregates (2-0.25 mm) contained the highest OC content and microaggregates (0.025 mm) had the highest OC stocks regardless of soil depth and stand age. Across the afforestation chronosequence, OC content and stock in bulk soil positively correlated with large macroaggregate (2 mm) amounts and small macroaggregate (2-0.25 mm) associated OC dynamics (P 0.01). These results indicated that changes in bulk soil OC dynamics mainly depend on changes in the proportion of large macroaggregates and in the OC dynamics associated with small macroaggregates after RP afforestation.

Soil microorganisms play crucial roles between plants and soil following afforestation. However, the relationship between the microbial community and carbon:nitrogen:phosphorus (C:N:P) stoichiometry in the plant&ndash, soil&ndash, microbe continuum remains unclear. In this study, we investigated this relationship by collecting plant and soil samples from Caragana korshinskii Kom. plantations with different years of afforestation (17-, 32-, and 42-year-old plantations), and from farmland. Illumina sequencing of the 16S rRNA and internal transcribed spacer (ITS) ribosomal RNA was used to examine the soil microbial community and the C, N, and P concentrations in plants, soil, and microbial biomass. Other soil characteristics were also measured. The results showed that the C and N concentrations in plants (leaves, herbs, and litter), soil, and microbial biomass increased as the vegetation restoration stage increased, but the P concentration in leaves and herbs slightly decreased. The C:P and N:P ratios in the plant&ndash, microbe continuum substantially increased over time, particularly that of the microbial biomass. These results suggest that the unbalanced increase of C, N, and P following vegetation restoration may result in a P limitation in plant&ndash, soil systems. Moreover, bacterial and fungal alpha diversity significantly increased following afforestation. Afforestation had a greater impact on bacterial diversity (both alpha and beta diversity) than did fungal diversity. Among the dominant bacterial taxa, Proteobacteria increased significantly with afforestation time, whereas Actinobacteria decreased and Acidobacteria peaked in 32-year-old C. korshinskii plantations. However, there were no significant changes in the dominant fungal taxa. Collectively, we found that microbial diversity and dominant phyla were closely associated with the C:P and N:P ratios in the plant&ndash, microbe continuum, particularly the N:P ratio. These results suggest that microbial diversity and composition may be limited by the imbalances of C, N, and especially P in afforested ecosystems, which provides evidence of linkages between microbial diversity and plant&ndash, soil systems in afforested ecosystems and could help in improving the predictions of sustainably restoring C. korshinskii plantations.

Non-point source pollution (NPSP) is a major challenge for current global water resources. The output characteristics of pollutants under different land use types are very important for controlling NPSP. In this study, long-term positioning monitoring and an analysis of rainfall runoff from different land use types were used to evaluate a typical watershed in the water source area of the middle route of the South-to-North Water Diversion Project (MR-SNWDP). The results show significant differences in nitrogen and phosphorus content in the runoff water bodies of various land use types. The nitrogen and phosphorus content in the MR-SNWDP was directly related to rainfall intensity and the fertilization period in the runoff following fertilization of farmland and vegetable plots. This nitrogen and phosphorus content was also observed to be significantly higher in the fertilization period than in other periods. The loss of nitrogen and phosphorus in forestland was greatly affected by rainfall intensity. Nitrogen in runoff comes primarily from farmland and vegetable fields, where its main form is nitrate nitrogen (NN). Vegetable fields are the main source of phosphorus, where its primary form is soluble phosphate (PO43&minus, P). Nitrogen and phosphorus have a defined incubation period during the dry season. Farmland and vegetable fields receive less rainfall during the dry season and it is difficult to form effective runoff, this allows nitrogen and phosphorus deposition. The runoff formed by the first rainfall at the beginning of the flood season (April or May) will carry a large amount of nitrogen and phosphorus from the soil into water bodies. Therefore, it is crucial to pay careful attention to the season when attempting to control NPSP.

Understanding the association between soil organic carbon (SOC) and texture under different climatic conditions is important for assessing the effects of future climate changes on SOC stocks. In this study, we conducted a climatic gradient experiment covering three climate types (humid, sub-humid, and semi-arid) with a steep rainfall ranging from 345 to 910 mm, and specifically determined SOC dynamics, clay content, and vegetation and soil characteristics. The results showed that, from semi-arid to humid regions, SOC stocks, SOC, and clay content increased synchronously and were closely related in layers of depths of both 0&ndash, 10 and 10&ndash, 20 cm. In contrast, under similar climatic conditions, SOC dynamics were mainly affected by vegetation and soil characteristics, especially total nitrogen and total phosphorus dynamics, but not the soil clay content. Therefore, these results suggest that the relationship between SOC stocks and clay content depended on scale sizes. Specifically, on a larger scale with different climatic gradients, the climate may partly determine the changes in SOC and clay dynamics, whereas, at a smaller scale where climate type does not vary considerably, the changes in SOC stocks and clay content may be related to vegetation diversity and soil nutrient dynamics. These results may contribute to future model development and the projection of changes in soil carbon storage.

Soil respiration (SR) is an important process in the carbon cycle. However, the means by which changes in understory plant community traits affect this ecosystem process is still poorly understood. In this study, plant species surveys were conducted and soil samples were collected from forests dominated by black locust (Robinia pseudoacacia L.), with a chronosequence of 15, 25, and 40 years (RP15, RP25, and RP40, respectively), and farmland (FL). Understory plant coverage, evenness, diversity, and richness were determined. We investigated soil microbial biomass carbon (MBC), nitrogen (MBN), phosphorus (MBP), and stoichiometry (MBC:MBN, MBC:MBP, and MBN:MBP). Soil enzyme assays (catalase, saccharase, urease, and alkaline phosphatase), heterotrophic respiration (HR), and autotrophic respiration (AR) were measured. The results showed that plant coverage, plant richness index (R), evenness, and Shannon-Wiener diversity were higher in RP25 and RP40 than in RP15. SR, HR, and AR were significantly higher in the forested sites than in farmland, especially for SR, which was on average 360.7%, 249.6%, and 248.2% higher in RP40, RP25, and RP15, respectively. Meanwhile, catalase, saccharase, urease, and alkaline phosphatase activities and soil microbial C, N, P, and its stoichiometry were also higher after afforestation. Moreover, significant Pearson linear correlations between understory plants (coverage, evenness, diversity, and richness) and SR, HR, and AR were observed, with the strongest correlation observed between plant coverage and SR. This correlation largely depended on soil enzymes (i.e., catalase, saccharase, urease, and alkaline phosphatase), and soil microbial biomass C, N, and P contents and its stoichiometry, particularly urease activity and the MBC:MBP ratio. Therefore, we conclude that plant communities are drivers of soil respiration, and that changes in soil respiration are associated with shifts in soil enzyme activities and nutrient stoichiometry.

The afforestation of abandoned land could offer opportunities to sequester soil organic carbon (SOC), promote nutriment elements cycling, improve plant diversity in the plantation understory and provide ecosystem services. The objectives of this study were to identify plant diversity in the plantation understory, quantify the changes in SOC and total nitrogen (TN) storage in deep soil, assess the SOC, TN, and total phosphorus (TP) stoichiometries, and investigate their relationships in the Loess Plateau Region (LPR) undergoing long-term afforestation. Soil samples were collected at a soil depth of 0–200 cm under 30-yr old Robinia pseudoacacia L. and adjacent abandoned sites, and SOC, TN and TP were determined in different soil depth. Additionally, plant composition and diversity in the plantation understory were evaluated. The results showed that land subjected to long-term afforestation had greater plant coverage, plant density, richness index ( R ) and Shannon–Wiener diversity ( H ) compared to abandoned land communities ( P P P P R CN , R CP , and R NP ratios.

Energy crisis is receiving attention with regard to the global economy and environmental sustainable development. Developing new energy resources to optimize the energy supply structure has become an important measure to prevent energy shortage as well as achieving energy conservation and emission reduction in China. This study proposed the concept of energy agriculture and constructed an energy agricultural technical support system based on the analysis of energy supply and demand and China’s foreign dependence on energy resources, combined with the function of agriculture in the energy field. Manufacturing technology equipment and agricultural and forestry energy, including crop or forestry plants and animal feces, were used in the system. The current status and future potential of China’s marginal land resources, energy crop germplasm resources, and agricultural and forestry waste energy-oriented resources were analyzed. Developing the function of traditional agriculture in food production may promote China’s social, economic, and environmental sustainable development and achieve energy saving and emission reduction.

Farmers’ pro-ecological intentions (PEI) after ecological rehabilitation are crucial to the sustainability of ecological conservation achievements and attract attention from policy-makers and managers. However, studies regarding multiple factors and their mechanism of influence on farmer's PEI are limited in fragile environmental areas. We conducted a household survey that measures the perceptions and attitudes, and the individual, demographic, and economic properties of 2025 farmers in the Loess Plateau of China. Results showed that only 28.74% of the respondents intended to apply the pro-ecological behavior after ecological restoration. The structural equation model reported a high explanatory power of 77.6% for farmers’ PEI. Farmers’ intentions to apply pro-ecological behaviors are jointly affected by various factors, with their perceptions and attitudes found to be the most influential factor and a vital link to other factors. Farmers’ individual, demographic, and economic factors also showed significant effects. Younger male farmers with higher education degrees, and better self-assessment of their abilities and perception of environmental improvement tend to state a greater intention to apply pro-ecological behaviors after the ecological rehabilitation. Results suggest that policy-makers and managers wanting to encourage farmers taking pro-ecological actions after ecological programs should value both enhancing farmers’ abilities to conserve ecological achievements and their perceptions of ecological benefits.

A pretreatment process for hydrogen peroxide (H2O2) was optimized to enhance the biodegradation performance of rice straw and increase biogas yield. A determination experiment was conducted under predicted optimal conditions. Optimization was implemented using response surface methodology. The effects of biodegradation and the interactive effects of pretreatment time (PT), H2O2 concentration (HC), and substrate to inoculum ratio (S/I) on methane yield were investigated. The lignin, cellulose, and hemicellulose of rice straw were significantly degraded with increasing HC. The optimal conditions for the use of pretreated rice straw in anaerobic digestion were a 6.18-d PT, 2.68% HC (w/w total solid), and 1.08 S/I; these conditions result in a methane yield of 288 mL g−1 volatile solids (VS). A determination coefficient of 95.2% was obtained, indicating that the model used to predict the anabolic digestion process has a favorable fit with the experimental parameters. The determination experiment resulted in a methane yield of 290 mL g−1 VS, 88.0% higher than that of untreated rice straw. Thus, H2O2 pretreatment of rice straw can be used to improve methane yields during biogas production.

In the present paper, we investigated the effects of afforestation on nitrogen fractions and microbial communities. A total of 24 soil samples were collected from farmland (FL) and three afforested lands, namely Robinia pseudoacacia L (RP), Caragana korshinskii Kom (CK), and abandoned land (AL), which have been arable for the past 40 years. Quantitative PCR and Illumina sequencing of 16S rRNA genes were used to analyze soil bacterial abundance, diversity, and composition. Additionally, soil nitrogen (N) stocks and fractions were estimated. The results showed that soil N stock, N fractions, and bacterial abundance and diversity increased following afforestation. Proteobacteria, Acidobacteria, and Actinobacteria were the dominant phyla of soil bacterial compositions. Overall, soil bacterial compositions generally changed from Actinobacteria (Acidobacteria)-dominant to Proteobacteria-dominant following afforestation. Soil N fractions, especially for dissolved organic nitrogen (DON), were significantly correlated with most bacterial groups and bacterial diversity, while potential competitive interactions between Proteobacteria (order Rhizobiales) and Cyanobacteria were suggested. In contrast, nitrate nitrogen (NO3−-N) influenced soil bacterial compositions less than other N fractions. Therefore, the present study demonstrated that bacterial diversity and specific species respond to farmland-to-forest conversion and hence have the potential to affect N dynamic processes in the Loess Plateau.

In the Loess Hilly Region of China, the widespread conversion of cropland to forestland and grassland has resulted in great increased in organic carbon (C), nitrogen (N) and phosphorus (P) stocks in the shallow soil layers. However, knowledge regarding changes in C, N, and P in deep soil is still limited. To elucidate the responses of deep soil C, N, and P stocks and stoichiometry in response to changes in land use, the soil from a 0-200 cm soil profile was collected from the following three typical land use patterns in the heartland of the region: forestland, grassland, and cropland. Compared with cropland, forestland and grassland had improved soil organic carbon (SOC) and total nitrogen (TN) contents and stocks at most soil depths but decreased total phosphorus (TP) contents and stocks. At soil depths of 0-200 cm in the forestland and grassland, the cumulative SOC stocks were improved by 34.97% and 7.61%, respectively, and the TN stocks were improved by 54.54% and 12.47%, respectively. The forestland had higher SOC, TN and TP contents and stocks compared to the grassland in almost all soil layers. The soil depths of 100-200 cm contained the highest percentages of SOC, TN and TP stocks (47.80%-49.93%, 46.08%-50.05% and 49.09%-52.98%, respectively). Additionally, the forestland and grassland showed enhanced soil C:P, N:P and C:N:P ratios, and the forestland had higher C:P, N:P and C:N:P ratios compared to the grassland. Furthermore, the SOC and TN stocks had significant impacts on the soil C:N, C:P and N:P ratios. It was concluded that afforestation was the best choice for soil nutrient restoration of degraded land, and deep soil provided an extremely important resource for evaluating soil C, N and P pools and cycling.

Artificial vegetation restoration can induce variations in accumulation and distribution of soil carbon (C), nitrogen (N) and phosphorus (P). However, little is known about variations in soil C, N and P nutrient fraction stratification following artificial vegetation in Loess Plateau China. Based on the hypothesis that re-vegetated can improve soil quality and stratification ratios (SR) can be used as an indicator to evaluate soil quality. This study measured contents and storages of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP) and their SRs in topsoil (0–20 cm) and subsoil (20–60 cm) in three 30-year re-vegetated lands that had been converted from arable land (Robinia pseudoacacia L., Caragana Korshinskii Kom. and abandoned cropland with low interferences and few management measures) and one slope cropland (SC) as a control for three soil profiles(0–20 cm, 20–40 cm and 40–60 cm) from June 2009 to June 2013. The results showed that the contents and storages of SOC, TN and TP in re-vegetated land were significantly higher than those in the SC in both topsoil and subsoil. The storages of SOC, TN and TP in the topsoil (0–20 cm) of the re-vegetated lands increased by 16.2%-26.4%, 12.7%-28.4% and 16.5%-20.9%, respectively, and increased by smaller but significant amounts in subsoil from 2009 to 2013. The SRs for SOC, TN and TP in the re-vegetated lands were mostly >2 (either for 0–20:20–40 cm or 0–20:40–60 cm) and greater than that in the SC. The SRs showed an increasing trend with increasing restoration age. The results also showed that the land use type and soil depth were the most influential factors for the SRs and storages, and the SRs of SOC and TN had significantly positive correlations with their storages. The SRs were concluded to be a good indicator for evaluating the soil quality, which can be significantly enhanced through vegetation restoration. Moreover, vegetation restoration can significantly enhance SOC, TN and TP accumulation in both topsoil and subsoil.

This study investigated a typical secondary Betula platyphylla forest in the Ziwuling Mountains, Loess Plateau, China. In the sample plot, the DBH (diameter at breast height) class structure of B. platyphylla was bimodal. Individuals with small and large DBH values were abundant. The DBH structures of Quercus wutaishanica and Pinus tabulaeformis were close to that of the logistic model, thus suggesting the increasing population of these species. B. platyphylla and Populus davidiana showed random spatial distributions at almost all scales. However, Q. wutaishanica and P. tabulaeformis were significantly clumped at small scales. B. platyphylla had a negative spatial relation with Q. wutaishanica at small spatial scales. P. tabulaeformis and Q. wutaishanica showed negative spatial correlations at small scales, but they had positive correlations at large scales. These results suggest that P. tabulaeformis and Q. wutaishanica shared habitat preferences at these scales. In the future, the secondary B. platyphylla forest in the Ziwuling Mountains in the Loess Plateau will probably change into a multi-species mixed forest (Quercus-Pinus mixed forest). Assisted restoration strategies must be employed to improve the regeneration dynamics of the forest in the long term.

The lime pretreatment process for rice straw was optimized to enhance the biodegradation performance and increase biogas yield. The optimization was implemented using response surface methodology (RSM) and Box-Behnken experimental design. The effects of biodegradation, as well as the interactive effects of Ca(OH)2concentration, pretreatment time, and inoculum amount on biogas improvement, were investigated. Rice straw compounds, such as lignin, cellulose, and hemicellulose, were significantly degraded with increasing Ca(OH)2concentration. The optimal conditions for the use of pretreated rice straw in anaerobic digestion were 9.81% Ca(OH)2(w/w TS), 5.89 d treatment time, and 45.12% inoculum content, which resulted in a methane yield of 225.3 mL/g VS. A determination coefficient (R2) of 96% was obtained, indicating that the model used to predict the anabolic digestion process shows a favorable fit with the experimental parameters.

This study applies the environmental Kuznets curve to test the relationship between the regional economic growth and the different types of agricultural nonpoint source pollution loads in the Ningxia Yellow River irrigation area by using the Johnes export coefficient method. Results show that the pollution load generated by crop cultivation and livestock-breeding industries in the Ningxia Yellow River irrigation area shows an inverted U-shaped feature; however, this feature is absent in living-sewage pollution load. Crop pollution has shown a decreasing trend since 1997 because of the increased per capita income of farmers. Livestock-breeding pollution load reached its turning point when the per capita income of farmers reached 8386.74 RMB. Therefore, an increase in the per capita income of farmers corresponds to an increase in the livestock-breeding pollution load in the Ningxia Yellow River irrigation area.

Goat manure (GM) is an excellent raw material for anaerobic digestion because of its high total nitrogen content and fermentation stability. Several comparative assays were conducted on the anaerobic co-digestion of GM with three crop residues (CRs), namely, wheat straw (WS), corn stalks (CS) and rice straw (RS), under different mixing ratios. All digesters were implemented simultaneously under mesophilic temperature at 35±1 °C with a total solid concentration of 8%. Result showed that the combination of GM with CS or RS significantly improved biogas production at all carbon-to-nitrogen (C/N) ratios. GM/CS (30:70), GM/CS (70:30), GM/RS (30:70) and GM/RS (50:50) produced the highest biogas yields from different co-substrates (14840, 16023, 15608 and 15698 mL, respectively) after 55 d of fermentation. Biogas yields of GM/WS 30:70 (C/N 35.61), GM/CS 70:30 (C/N 21.19) and GM/RS 50:50 (C/N 26.23) were 1.62, 2.11 and 1.83 times higher than that of CRs, respectively. These values were determined to be the optimal C/N ratios for co-digestion. However, compared with treatments of GM/CS and GM/RS treatments, biogas generated from GM/WS was only slightly higher than the single digestion of GM or WS. This result was caused by the high total carbon content (35.83%) and lignin content (24.34%) in WS, which inhibited biodegradation.

The World Wide Web gains more and more popularity within China with more than 1.31 million websites on the Chinese Web in June 2007. Driven by the economic profits, cyber criminals are on the rise and use the Web to exploit innocent users. In fact, a real underground black market with thousands of parti cipants has developed, which brings together malicious users who trade exploits, malware, virtual assets, stolen credentials, and more. In this chapter, we provide a detailed overview of this underground black market and present a model to describe the market. We substantiate our model with the help of measurement results within the Chinese Web. First, we show that the amount of virtual assets traded on this underground market is huge. Second, our research proves that a significant amount of websites within China’s part of the Web contain some kind of malicious content: our measurements reveal that about 1.49% of the examined sites contain malicious content that tries to attack the visitor’s browser.